Here is the tutorial I did for the Quilted Paradise Newsletter.
http://www.quiltedparadise.com/n/038-oqk.jsp - mouse pad--star point
and I also did one in my Dresden Kaleidoscope book - this is the one I use.
I made mine with just one layer of traditional poly batting.
I don't have any problem with it at all. My mouse works just fine on it.